1. Field of the Invention
The present invention relates generally to micro aerial vehicles. It relates more particularly to maximizing the flapping amplitude of ornithoptic micro aerial vehicles.
2. Description of the Related Art
The fundamental technology objective that motivates the present invention is the creation of a highly agile micro aerial vehicle (MAV), capable of rapidly performing reconnaissance missions in highly congested environments, such as the interior of a building, beneath a forest canopy, or within a network of tunnels and caves. Several biologically inspired concepts for the design of such a vehicle have been proposed that would employ an ornithoptic (flapping wing) system to enable the types of agile maneuvers and flight modes exhibited by insects and humming birds. Numerous technical challenges currently prevent the creation of such a device, including miniaturization of lightweight actuation mechanisms, structures, electronics and power sources. These are the basic building blocks that would be required to create an agile ornithoptic MAV. But even beyond the technical challenge of creating those building blocks lies the challenge of integrating them into an efficient, controllable flight system.
Current research efforts in flapping flight systems generally acknowledge the significance of operating at resonance, but the current practice is simply to estimate the resonant frequency of the flapping system based on observation, and then to drive the system with an open-loop periodic excitation at this frequency. Current and past research efforts using such an approach have attempted to provide ornithoptic MAV designs employing flexible wing structures, but to date no efforts have been made to develop an effective closed-loop self-tuning circuit to enable the flapping system to be driven at its resonant frequency.
The basic disadvantage of the prior art is that it assumes that the resonant frequency has been appropriately identified through a-priori testing and that it is invariant with flight mode, ambient conditions, and mechanical wear or damage to the system. Furthermore, if the significant effect of manufacturing variation in a one-off fabrication type of environment is to be accounted for, the resonant frequency of each article must be individually identified via a-priori testing.